2'-O-methylation
2'-O-methylation (2'-O-Me) is a common nucleotide epitranscriptomics modification of ribosomal RNA (rRNA). The rRNA is transcribed from DNA and then used to create proteins through translation.[1] The resulting protein would normally be solely dependent on the gene it was translated from, but the methylation of the RNA would influence the outcome of the protein as well.[1] This modification to the rRNA is done via ribonucleoprotein (snoRNP)[2] where a methyl group is added to the 2' hydroxyl of the ribose moiety of any nucleotide (Nm)[3] producing a methoxy group. The modification of one Nm creates more stabilization in the structure by 0.2kcal/mol[4] which is more enthalpically favorable. 2'-O-methylated nucleotides are mostly found in post-translational ribosomal RNA and small nuclear RNA located in the ribosome and spliceosome.[5] Currently, about 55 2'-O-methylations have been identified in yeast alone and 106 in humans[6] and deposited in RNA Modification Base (RMBase) database.[7]
This modification is able to stabilize the structure of RNA while preventing it from undergoing hydrolysis as the hydroxyl group is replaced.[2] A technique was developed based on this property called RiboMethSeq to quantify the amount of modifications existing in a sample of rRNA.[8] RNA is a short lived molecule and each of the types vary in its longevity in the cell. Ribosomal RNA exists longer in the cell before degradation so utilizing 2'-O-Met would aid in stabilizing its structure. The epitranscriptomics of this particular RNA modification occurs post-translation, causing a change in the resulting protein without the DNA being altered.[9]
Having chemical properties intermediate between RNA and DNA, 2'-O-methylation is presumed to have been one of the reactive group of RNA molecules on early Earth that would have given rise to DNA.[10]